package util

import (
	"encoding/hex"
	"testing"
)

func TestRandomHexStringLength(t *testing.T) {
	tests := []struct {
		name           string
		byteLength     int
		expectedLength int
	}{
		{"no bytes at all", 0, 0},
		{"one byte", 1, 2},
		{"eight bytes", 8, 16},
		{"sixteen bytes", 16, 32},
		{"thirty-two bytes", 32, 64},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			got, err := RandomHexString(test.byteLength)
			if err != nil {
				t.Fatalf("did not expect an error, got %v", err)
			}
			if len(got) != test.expectedLength {
				t.Errorf("expected a string of %d characters, got %d (%q)", test.expectedLength, len(got), got)
			}
			if _, err := hex.DecodeString(got); err != nil {
				t.Errorf("expected valid hexadecimal, got %q: %v", got, err)
			}
		})
	}
}

func TestRandomHexStringRejectsNegativeLength(t *testing.T) {
	got, err := RandomHexString(-1)
	if err == nil {
		t.Errorf("expected an error for a negative length, got %q", got)
	}
}

func TestRandomHexStringDiffersBetweenCalls(t *testing.T) {
	seen := make(map[string]struct{})

	for i := 0; i < 100; i++ {
		value, err := RandomHexString(16)
		if err != nil {
			t.Fatalf("did not expect an error, got %v", err)
		}
		if _, repeated := seen[value]; repeated {
			t.Fatalf("got the same string twice: %q", value)
		}
		seen[value] = struct{}{}
	}
}